Nation by Terry Pratchett
Doubleday, £16.99; 300pp Buy the book here

The Folklore of Discworld by Terry Pratchett and Jacqueline Simpson
Doubleday, £17.99; 368pp Buy the book here

The similarities between children and savages have often been noted by adults. Its greatest expression arrived in Lord of the Flies, but there are plenty of children's books that explore the less tragic delights of hunting and gathering.

Michelle Paver's consist-ently splendid Chronicles of Ancient Darkness (the fifth book in the series, Oath Breaker, is also published this month) is an example of how gripping and life-enhancing the genre can be, but Terry Pratchett's Nation is another.

Mau, its hero, is making the formal journey from the boys' island to become a man of the island people who call themselves the Nation. When a great wave comes and kills everyone he knows, he must discover how truly to become a man without any of the customs and supports of his society.

Also shipwrecked is a nice, well-bred English girl whose father has just become the King of England. Sensible, sensitive and resourceful, Daphne is a passionate scientist whose intellectual curiosity has been stifled by a repressive grandmother. How they learn to communicate, find food, deli-ver a baby and make the Nation's beer from a poisonous plant is all thrillingly described in the first half of the book.

As her name suggests, Daphne is the chrysalis for one of Pratchett's most dazzling and dauntless heroines, as tough as Granny Weatherwax and as brave as Tiffany in A Hat Full of Sky.

Yet it is Mau, struggling with the near-madness that the destruction of his people brings about, who is particu-larly sympathetic. His ancestral grandfathers hector him in capital letters: “EVERYTHING THE NATION WAS, YOU ARE! WHILE YOU ARE, THE NATION IS! WHILE YOU REMEMBER, THE NATION LIVES!”

The internal drama of his predicament outweighs the external. Unlike the Discworld novels, the magic and gods appealed to may not exist.

It is hard not to see the terrible wave crashing through Mau's people's memories as an extended metaphor for the Alzheimer's that has stricken Pratchett's ever-fertile mind, and Mau's struggle to recreate something new out of devastation akin to the author's grappling with an assault on his creative powers. Yet like all serious writers of fantasy, Pratchett has always been proccupied with death. It is curious how those who dislike this form of literature believe it to be escapist when in fact it tends towards the opposite, dramatising the sorrow of eternal loss.

“When much is taken, something is returned,” a wise old man tells Mau, and if our hero and heroine lose their adult guides they also lose the unnecessary constraints of their respective cultures.

Their gathering together of a scattered, shattered people is achieved under terrific pressure, for as well as sharks to scare away and treasure to discover, there are the traditional cannibal enemies of the Nation about to invade and two villains from Daphne's shipwrecked boat. How can a boy, a girl, a toothless old woman and a mother with a newborn baby possibly hope to survive? How can they learn each other's language and interpret their growing feelings for each other? Like other Pratchett novels, Nation is set in a parallel universe, though it is not that of Discworld: of course, every fiction is set in a parallel universe, as the intelligent reader should notice, but often fails to.

This is an enchanting novel, written in clear, direct English with less of the Baroque jokes and digressions that Pratchett's fans enjoy, though with plenty left in to leaven its serious concerns. Despite his best-selling status, and his Carnegie medal, I still think that Terry Pratchett is one of the most interesting and critically underrated novelists we have. Books such as the forthcoming guide to his invented universe, The Folklore of Discworld - co-authored with the eminent folklorist Jacqueline Simpson - emphasise his irreverence and drollery, but they also add to the impression that he is as much an acquired taste as warm English beer. For those resistant to the wilder shores of fantasy, however, Nation is as good a place as any to start.